Separations of polynucleotides such as DNA have been traditionally performed using slab gel electrophoresis or capillary electrophoresis. However, liquid chromatographic separations of polynucleotides are becoming more important because of the ability to automate the analysis and to collect fractions after they have been separated. Therefore, columns for polynucleotide separation by liquid chromatography (LC) are becoming more important.
High quality materials for double stranded DNA separations previously have been based on polymeric substrates disclosed in U.S. Pat. No. 5,585,236, to Bonn, et al. (1996), which showed that double-stranded DNA can be separated on the basis of size with selectivity and performance similar to gel electrophoresis using a process characterized as reverse phase ion pairing chromatography (RPIPC). However, the chromatographic material described was limited to nonporous beads substituted with alkyl groups having at least 3 carbons because Bonn, et al. were unsuccessful in obtaining separations using polymer beads lacking this substitution. Additionally, the polymer beads were limited to a small group of vinyl aromatic monomers, and Bonn et al. were unable to effect DNA separations with other materials.
A need continues to exist for chromatographic methods for separating polynucleotides with improved separation efficiency and resolution.